含Nb高钼H13钢凝固过程中合金元素的微观偏析

Microsegregation of Alloying Elements in H13 Steel with Nb-microalloying and High Molybdenum during Solidification Process

利用Thermo-calc热力学计算软件中的Scheil模块和Ploy-3模块,对含Nb高钼H13钢的凝固过程及平衡析出相与温度的关系进行了模拟与热力学研究,同时讨论了钢中合金元素的偏析行为。结合Scheil-Gulliver方程和Origin8.0软件对合金元素偏析结果进行了线性回归,得到了合金元素的平衡分配系数。模拟结果表明,凝固过程中,当固相率达到90%时由于MC型碳化物的析出,导致合金元素中C、Nb、V的质量分数急剧下降;元素C、Si、Mn、Cr、Mo、V和Nb的平衡分配系数k0均小于1,模拟结果与文献数据有较好的一致性。提出在1250～1270℃保温4～6h高温均匀化处理并辅以大变形量的锻造,可以减轻偏析,从而提高H13钢的综合力学性能。

Simulation of solidification process and the thermodynamic relation between temperature and equilibrium precipitated phases in H13 steel with Nb and high Mo contents have been investigated based on the Scheil module and Ploy-3 module in the Thermo-calc thermodynamic software. Meanwhile, the segregation behavior of alloying elements in the steel tested was also discussed. The result of element segregation was presented and equilibrium partition coefficient of alloy element was obtained by linear regressions depending on the Scheil-Gulliver equation and the Origin8.0 soft. The results show that the mass fractions of C, Nb and V is decreased sharply when solid fraction reaches 90% as a result of MC carbide precipitation. The equilibrium partition coefficients KO of C, Si, Mn, Cr, Mo, V and Nb are less than 1, which is consistent with literature data. The high temperature homogenizing treatment process atn （1 250～ 1 270）℃× （4～6） hours and multi-passes forging has been suggested, which reduces segregation and improves the comorehensive proaerties of the steel tested.